Carbon Steel Grating

Steel is commonly considered carbon steel when no minimum content is specified for any alloying element (for example, aluminum, chromium, nickel, molybdenum, vanadium, etc.) or any other element added to obtain a desired alloy effect. The manganese does not exceed 1.65%, the specified minimum for copper in not below .40% or exceed .60% and silicon does not exceed .60%.

The second two numbers in AISI-SAE designations indicate the approximate carbon content for steel (for example, in 1018 the carbon range is .15% to .20%; .18% [shown as "18"] is the approximate carbon content).